Gas compression method and apparatus



. 22, 1970 H. GIDDINGS GAS COMPRESSION METHOD AND APPARATUS 3 Sheets-Sheet 1 Filed Sept. 2'7, 1968 P m E V N w m S S E ms M O C E D lw N w E L fix n m m c X E I IN T E L P N M w 0 S C a R.\. P M O C |w N 7 m T m8 D m mmnmmmma BY EDWARD H.G|DD|NGS ATTORNEY Dec. 22, 1970 H, lD s 7 3,549,278

GAS COMPRESSION METHOD AND APPARATUS Filed Sept. 27. 1968 3 Sheets-Sheet 2 I I f' 2 I I L 1 l3 1 I i .J I ,1 l I 4 n I 1 U F/g 3 Fig-4 l glFggz l6 2/ 22 4/ 22 2/ 5 Fig-8 v D INVENTOR EDWARD H. GIDDINGS BY fat/WW ATTORNEY Dec. 22. 1970 E. H. GIDDINGS GAS COMPRESSION METHOD AND APPARATUS Filed Sept. 27, 1968 3 Sheets-Sheet 5 INVENTOR EDWARD H. GIDDINGS ATTORNEY United States Patent 3,549,278 GAS COMPRESSION METHOD AND APPARATUS Edward H. Giddings, 1811 Woodrow St., Wichita Falls, Tex. 76301 Filed Sept. 27, 1968, Ser. No. 763,425 Int. Cl. F041: 35/00 US. Cl. 417-349 18 Claims ABSTRACT OF THE DISCLOSURE A gas compressor having a constant volume system including a closed cylindrical chamber with a displacement piston therein defining two variable volume spaces each of which is connected by ducting to an end of a thermal regenerator. An inlet check valve is provided through which gas at a given pressure and temperature is inducted, while transferring heat from the gas to the thermal regenerator, into a first variable volume space. Subsequent axial motion of the piston moves the gas from the first space back through the thermal regenerator, from which heat is transferred to the gas, to the second space. An outlet check valve is provided through which the reheated gas is exhausted from the system upon attaining a pressure greater than that at which inducted.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to an improved method and apparatus for compressin gases. More particularly, this invention concerns the use of the heat content of a gaseous medium to accomplish the increased pressurization of that medium or another.

The method and apparatus for compressing gases herein disclosed is applicable to any gaseous medium which does not undergo a change of state within the pressure range involved. The method is particularly adapted to handling large quantities of gases at low compression ratios and is adaptable to a multitude of uses. For example, the compressor may be used in treatment of the hot gas effluent from the burning or gasification of waste or other materials, for reclaiming chemical constituents from hot gases, as a recovery and flow inducing means in gas phase chemical synthesis or as means permitting use of low grade, dirty or wet fuels as a source of energy.

Considerable attention has been given to recovery of the heat of combustion from incineration of wastes for heating, refrigeration and use with a variety of energy conversion techniques in the production of commercial and industrial power. The usual technique employed is to use the hot gases from an incinerator as a supplemental heat source for a boiler fired steam plant. More sophisticated approaches have incorporated the incinerator as the furnace element of a steam generating boiler with which conventional prime movers are driven. Attempts have also been made to drivegas turbines directly with the hot gas effluent from the incineration process, however, the presence of solids, corrosive contaminants and excess moisture have proved detrimental to the dynamic parts.

It is anticipated that waste can, upon proper treatment, assume importance as a source of raw materials, along with natural resources, to be utilized in industrial processes. Recovery of chemical constituents, from the incineration of waste, promises an economically appealing solution to waste disposal. Industrial use of gases requires a reasonable uniformity of composition and delivery at consistent physical conditions of pressure, temperature and humidity. It is further necessary that the hot gases be processed at the lowest practical cost in order for the chemicals extracted therefrom to be econ 4 3,549,278 Patented Dec. 22, 1970 nomically competitive with those derived from natural resources.

There is thus a need for a method to economically treat the hot gaseous effluent from waste incinerators to remove fly ash" solids and deliver the scrubbed gas at a reasonably uniform temperature and humidity and at a pressure exceeding that of the atmosphere. The key to an economically motivated universal use of incineration for waste disposal is the availability of ancillary equipment which will prevent environmental contamination and provide for the economic recovery of the products of combustion in a manner consistent with subsequent industrial processing.

The gas compressor herein disclosed provides three significant advantages when used in a refuse incineration system. First, the ability of the gas compressor to impose a suction head on the incinerator permits forced draft retrograde burning. In this manner the volatile components are cooked off the refuse and may be drawn through the incandescent zone thus assuring more complete combustion. Second, use of direct contact cooling with water droplets constitutes a scrubbing of the incinerator flue gas. Third, the flue gas leaves the gas compressor at a substantial pressure thus simplifying subsequent use of the gas.

Industrial and commercial power plants may take advantage of the new gas compression method to secure more eflicient operation. Pressure losses need no longer limit heat recovery capabilities of power plants as the low grade heat now only marginally useful to a steam power plant may, through gas compressors as herein described, be converted into clean pressurized working medium.

The subject gas compression method and apparatus may be advantageously employed in gas fractionization plants where the gas mixture to be fractionated is initially hot as the original compression capability constitutes a substantial proportion of plant cost. A commercially interesting example of this application is the separation of pure hydrogen and fractionation of the other constituents, from impure synthesis gas. Synthesis gas, a mixture of hydrogen, carbon monoxide and various minor constituents and impurities, is produced by the partial combustion of a fuel in oxygen and steam. The synthesis gas comes from the reaction at an elevated temperature suitable for the subject gas compression method. Gas compressors may be operated in stages with or without intermediate reheating to produce the pressure necessary for fractionation of the gas. The carbon monoxide may be recycled for its heating value, sulphur compounds may be recovered and sold and only the carbon dioxide need be discarded to the atmosphere. Hydrogen recovered in this fashion is itself commercially important or it may be used in a hydrox or hydrogen-air fuel cell to produce electric power.

Many applications for the subject gas compressor exist in chemical plants. The coolant liquid may itself be a reactant in some chemical process or it may be a solvent employed to extract constituents from a gaseous working medium. Controlled cooling may be used in the gas compressor to condense particular constituents from a hot gaseous stream with little reduction in the net temperature of the stream but with an increased pressurization or induced flow.

It is thus contemplated that the subject gas compressor will lend itself to a wide spectrum of applications in commerce and industry.

DESCRIPTION OF THE PRIOR ART Methods and apparatus are known which convey, pump and compress fluids using external sources of work or heat energy. Mechanical compressors capable of handling large quantities of gases are, as a rule, relatively complex and expensive to manufacture and maintain. Their etficiency is such that to handle large quantities of gases, for instance the eflluent from a large incinerator or power plant, at.

more and are relatively complex and expensive. Mechanically operative elements such as cylinders, pistons, vanes, bearings and seals of such devices become troublesome when subjected to high temperatures where lubrication or material strength fails.

Heat exchangers are commonly employed prior to and subsequent to mechanical compression, as well as intercoolers between stages, in an effort to limit gas temperatures and maintain efl'iciency. The heat discarded in cooling the gas often represents rejection of a significant portion of the work energy contributed to compress the gas. In positive displacement compressors it is often necessary to, filter the incoming gas to remove abrasive contaminants, add lubricant to the gas prior to compression and then filter the lubricant from the gas after compression.

Close tolerances and clearances are required in existing mechanical compressors to assure maximum volumetric efliciency. Aerodynamic elements such as nozzles, buckets and vanes of constant flow compressors are subject to loss of efliciency upon alteration of contours or surface characteristics occasioned by erosion by the working fluid. Where a compressor is driven by a mechanical power source the overall system efliciency is the product of the efficiencies of the separate components. Since efliciencies are always represented by a factor less than one the system efiiciency will always be less than that of either the power source or compressor separately.

It is apparent that a method of compressing gases is desirable which has the capacity to accomodate large quantities of gases, especially hot contaminated gases, at useful compression ratios. Additionally the means employed should require a minimum of complex precision components, operate without prior filtering, cooling or treatment of the gases and not be subject to deterioration from contaminants or excessive gas velocities. The system should also maintain its basic compression efficiency by limiting energy loss from heat rejection or incurring the necessity for heat or power input from external sources.

Techniques and apparatus have employed the contraction and expansion of a working fluid to pump or compress that fluid or another upon which the working fluid acts. A change of state of the working fluid has been used, for example, to effect its own compression. However, the techniques have required the application of externally supplied heat or mechanical power.

It is here contemplated that the subject gas compression method and apparatus will meet the above identified desirable characteristics with an additional advantage in its ability to clean or scrub the working gases or perform a solvent extraction therefrom during the compression process and thus be incorporated into a wide variety of industrial and commercial applications.

SUMMARY on THE INVENTION In recognition of the need for means to circulate and compress large quantities of gases in an economically practical manner for heating, energy conversion or recovery of the chemical constituents thereof, it is hereby proposed to provide a method and apparatus for compressing gases which utilizes the heat energy of the working gases thus requiring a minimum of externally supplied energy.

Another object is to provide an apparatus with a minimum of movable parts susceptible to the wear, erosion and corrosion characteristic of contaminated gases.

Another object is to provide an apparatus of such simplicity that the size required to handle large quantities of gases can be practically constructed and operated.

Another object is to provide a process in which the gases are scrubbed to remove solid particulate contaminants and subsequently reheat and pressurize the gas for delivery to means adapted to utilize the gas.

A further object is to provide a means by which the heat energy of a hot gas may be directly and efliciently applied to the compression of another gaseous fluid.

A still further object is to receive hot gases at or below atmospheric pressure, including the ability to create a vacuum or effect a draft on a furnace or incinerator, and deliver the cleaned and reheated gases therefrom in a pressurized condition preparatory to subsequently industrial processing.

Briefiy, in accordance with the present invention, there is provided a method for using the heat of working gases for their own compression. Contraction of a gaseous medium is used in the novel compression process in order to induct a quantity of the gas into a fixed volume system. A subsequent increase of the gas temperature and consequent pressure increase of the gaseous medium within the fixed volume system is used to expel part of the gas from the system at a higher pressure. Repetition of the cooling and heating cycle is employed to effect flow and delivery -of the gaseous medium at a pressure exceeding that of its source.

An apparatusfor practicing the described method comprises a closed cylindrical chamber containing a displacertype piston dividing the chamber into two variable volume spaces, means for moving the piston axially within the cylinder, an enclosed thermal regenerator column the extremities of which communicate by suitable gas conveying ducting to the variable volume spaces, check valves providing an inlet for gases and exit for reheated and pressurized gases and a cooling means situated in one of the variable volume spaces.

Other objects and advantages of the invention will become readily apparent to one skilled in the art from the following detailed description of preferred embodiments of the invention when read in connection with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematical vertical cross-sectional view through a gas compressor according to the present invention.

FIG. 2 is a graphical representation of the cyclical pressure characteristics of the gas compression method and diagrammatic illustrations of relative positions of mechanical parts and flow of heat energy and fluids during operation.

FIG. 3 is a diagrammatic illustration of a variation of a gas compressor according to the present invention.

FIG. 4 is a diagrammatic illustration of a variation of a gas compressor according to the present invention.

FIG. 5 is a diagrammatic illustration of the invention using an additive gas coolant.

FIG. 6 is a diagrammatic illustration of the invention using a sloshing liquid gas displacing means.

FIG. 7 is a diagrammatic illustration of the invention using-a heat energy from one gas to compress another gas.

FIG. 8 is a diagrammatic illustration of two compressors according to the present invention in complementary and interdependent relationship to each other.

"DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the figures in which like reference characters designate like parts, and particularly to FIG. 1, 'where is shown a diagrammatic illustration of a gas compressor in accordance with the invention in which a cylinder 10 is closed at both ends and the interior is divided into two variable volume sections, constituting a hot gas space 11 and a cool gas space 12, by a displacement-type reciprocating piston 13. The piston 13 is thermally insulating to transfer of heat through the piston from hot space 11 to cool space 12. A close fitting portion or seal 14 is provided at the lower or cool end of piston 13 which restricts passage of gases between piston 13 and the interior surface 15 of cylinder 10. A means is provided for imparting axial reciprocating movement to piston 13 within cylinder 10, as generally indicated at 20. Ports of ducts 16 provide gas conveying communication of the interior spaces 11 and 12 with the extrernities of an enclosed heat storage means or thermal regenerator 17 which is circumferentially disposed about the exterior of cylinder 10.

The cylinder 10, enclosed thermal regenerator 17 and communicating ducts 16 therebetween constitute an essentially gas tight system of constant volume. The hot space 11 of cylinder 10 is provided with oppositely acting pressure responsive one-way check valves 21 and 22. Check valve 21 provides an inlet for a gaseous working fluid from its source, for instance the hot gaseous exhaust of a waste disposal incinerator, as generally indicated by the gas flow arrow 1. Check valve 22, operable at a pressure substantially greater than that of inlet check valve 21 provides an exit for gases from the system, as generally indicated by the gas flow arrow 2, into whatever downstream reservoir is provided.

A cooling means is employed in the cool space 12 as represented by a coolant inlet 23 and pressure trapping drain 24 which permit introduction of a liquid coolant, for example Water, and continuous removal of the heated coolant without leakage of the gaseous working medium.

The length of piston 13 is depicted as approximately equal to one-half the length of the cylinder 10 and is consequently approximately equal to the length of stroke or travel of the piston within the cylinder. The length ratio of piston to cylinder is not essential to operation of the compressor, however such ratio assures that portions of the cylinder will not be alternately exposed to hot and cold gas.

The thermal regenerator 17 will in its most practical form be packed with metallic foil, screening or granulated heat absorptive materials such as glass of metal microspheres, as generally indicated at 18, thus providing a maximum amount of surface exposed to the gases flowing therethrough and presenting a minimum aerodynamic resistance to such flow. The same rationale applies to the coolant means wherein a liquid coolant, such as water, is sprayed or atomized as indicated at 25, into the cool space 12 to provide a maximum heat absorptive area. Once the coolant has absorbed heat it is drawn oil? through the drain 24 which is provided with an appropriate trap to prevent loss of the gaseous working fluid with the liquid coolant.

For maximum operational eificiency the entire system should be thermally insulated or lagged to prevent loss of heat from the system as heat is the primary operational energy utilized. Mechanical work input is required to move the piston within the cylinder but such input is only that required to move the piston against the nominal resistance of the thermal regenerator to gas flow therethrough.

In operation the gas compressor performs cyclically, that is the gas flow, heat flow and operation of mechanical components are interrelated and act in sequential fashion to efiect induction, compression and expulsion of the gaseous working medium. FIG. 2 is a stylized graphic representation of pressure conditions prevailing within the fixed volume system during one complete operational cycle of the compressor. Diagrammatic illustrations of parts relationship and energy and fluid flow are indicated in FIGS. 2a, 2b, 2c and 2d for the cyclical phases of induction, compression, expulsion and decompression respectively.

During the induction phase, indicated in FIG. 2a, piston 13 is in its top position and whatever residual quantity, w,- of gas is in the system is located principally in the cool space 12 below piston 13. The residual gas here exposed to the coolant means will be cooled to a temperature approaching the temperature T of the coolant with a consequential lowering of the pressure within the fixed volume system. As the pressure within the system is reduced below that pressure p at which gas is available from its source the check valve 21 will open and a quantity W1 of gas at pressure p and temperature T will be induced from its source into the system, as indicated by gas flow arrow 1, by reason of the lower pressure to which the system has been lowered. The inducted gas will, in flowing through thermal regenerator 17 transfer heat to the packing 18 thereof, as indicated by heat energy flow arrow 5, and to coolant means, as indicated by heat energy flow arrow 7. The quantity w; of the inducted gas is thus added to the residual quantity w within the system at a pressure 2 Downward movement of piston 13 will effect an initial increase in pressure causing pressure responsive inlet check valve 21 to close isolating the system from the source of gases. Continued downward movement of piston 13, as indicated in FIG. 2b, displaces gas from cool space 11 below piston 13 through thermal regenerator 17 into hot space 11 above piston 13. During return passage of the gas through regenerator 17 heat is transferred from packing 18 within regenerator 17 to the gas, as indicated by heat energy flow arrow 16, such that the gas within the fixed volume system will increase in temperature from T to a temperature T greater than T but less than T effecting an increase in pressure within the system.

At some point during the downward movement of piston 13 the pressure within the system will exceed the pressure p in a downstream reservoir, and a portion of the gas will be expelled through pressure responsive check valve 22, as indicated by gas fiow arrow 2 in FIG. 20, at pressure p greater than the pressure p at which inducted. Pressurized gas is thus discharged from the system until a residual quantity w of the gas remains in the system at pressure p and temperature T Subsequent upward movement of piston 13, as indicated in FIG. 2d, will displace the residual quantity of gas w from hot space 11 above piston 13 through thermal regenerator 17 into cool space 12 below piston 13. During passage of the residual gas through regenerator 17 heat from the gas is transferred to packing 18 within regenerator 17, as indicated by heat energy flow arrow 5, such that the residual quantity w, of the gas within the fixed volume system is reduced in temperature from T to T,,, thus effecting a drop in pressure within the system to the conditions when the cycle was initiated.

The amount of gas inducted, compressed and expelled in the method described will depend upon the ratio of absolute pressures at outlet and inlet as well as the ratio of temperatures attainable in the process. Assume, for instance, that absolute atmospheric pressure is applied to the inlet and that the outlet pressure is maintained at two atmospheres of absolute pressure. Assume further that the cool space 12 is maintained at an ambient temperature of 550 degrees Rankine and that hot space 11 is maintained at four times ambient temperature, or 2200 degrees Rankine, by the incoming gases. By the ideal gas laws only one-half the quantity of gas is required to fill the fixed volume of the system at two atmospheres and 2200 degrees Rankine as is required to fill that same volume at one atmosphere and 550 degrees Rankine. Therfore ideally one-half of the quantity W1 of the gas inducted will be discharged at the higher pressure.

It will be recognized that in actual operation the events as herein described occur as interrelated functions and the actions as described need not be completed prior to 3 It should also be evident that pressure of the gases within the fixed volume system will be essentially uniform throughout. A small differential pressure will be created across the displacing piston only in that degree sufiicient to overcome flow resistance of the thermal regenerator and to eifect flow of the gases therethrough. Thus the amount of work which must be done by some external means 20 acting to overcome mechanical and fluid friction and move the displacer piston is small.

Thermodynamic treatment of the method of compressing gas, as herein disclosed, is complicated bythe fact that different portions of the gas within the system undergo different cycles..The portion of the gaseous working fluid from which a net compression work output is realized operates according to the Ericsson cycle, composed of two isothermal and two constant pressure processes. Engines based upon the Ericsson cycle have been used to a limited extent for generating mechanical power, but the mean effective pressure of the cycle has proved too low to be competitive with modern engines, although the thermal efiiciency is relatively good. A low mean effective pressure is not detrimental to practical application of the instant invention and the good thermal efliciency remains an asset.

It should be recognized that the coolant means may be composed of a variety of components or combinations thereof. For example, reactants or solvents may prove useful as coolant means in applications of the disclosed compression method to chemical or extractive processes. Use of chemically reactive additives as coolant means will be more effective to enhance compressor efliciency where an endothermic rather than exothermic reaction results.

In FIG. 3 is shown another embodiment of the invention wherein the thermal regenerator 17 is not contiguous to nor a structural part of cylinder 10. A vertical thermal regenerator column 17 is illustrated but other types of thermal regenerative devices such as pebble beds, checker chambers and the like are applicable. The remotely located thermal regenerator 17 is connected to the ends of the cylinder by suitable gas conveying ports or ducting, as generally indicated at 16. The exhaust check valve 22 may be located intermediate the ends of the thermal regenerator column 17, as shown.-

Volumetric efficiency of the compressor will depend upon the ratio of volume swept by the displacer piston to free volume, including that of the ducting and thermal regenerator, of a particular system. An arrangement of potentially excellent volumetric efliciency is shown in FIG. 4 wherein the thermal regenerator 17, as represented by the packing 18 thereof, is incorporated into the structure of the displacement piston 13. Axial motion of the piston 13, with regenerator 17 enclosed, causes gases to flow from space 11 above piston 13 through thermal regenerator packing 18 to space 12 below the piston, or vice versa. Heat is transferred to or from the regenerator packing 18 and gases according to relative temperatures and direction of flow. The cooling means may be a refrigerated surface, as generally indicated at 26, convoluted or finned to most effectively cool the gases exposed thereto in the space 12 below piston 13.

A less eflicient manner of practicing the subject invention is illustrated in FIG. 5. The essential difierence from above described methods is that a coolant means, which neither, adds to nor subtracts from the quantity of gaseous working medium within the system, is omitted and a metered amount of cold gas is admitted and mixed with the working medium to effect a net cooling thereof. The admitted cooling gas contributes to the quantity of gas admitted, into the fixed volume system limiting the quantity of hot gas which may be inducted and thus detracting from the total heat energy available to perform compression work within the system. Although a less efficient practice of the process results the method may be applicable in cases where lower weight is an important consideration or other coolant means are not readily available.- Such practice may be used to extract power through compression of hot gases, from even an open fire at an admitted low level of efliciency.

In the device illustrated in FIG. 5 a check valve 27 and metering jet or constriction 28 is located in cylinder 10 adjacent cool space 12. The check valve 27 and metering jet 28 permit entry of a limited quantity of the surrounding atmosphere or other relatively cool gas, as indicated by gas flow arrow 3, in addition to the gaseous working medium inducted through inlet valve 21. The relatively cool gas 3 metered into the system thus performs a cooling function in addition to contributing to the quantity of gas admitted into the system.

An arrangement is illustrated in FIG. 6 by which the novel gas compression method here disclosed may be practiced utilizing a sloshing liquid displacer 31, similar to that of a Humphery engine. In this arrangement a sloshing liquid 31 is contained within a conduit 32 interconnecting two sections constituting a hot space 11 and a cool space 12. Appropriate ducting 16 interconnects spaces 11 and 12 through thermal regenerator 17. Inlet and exhaust valves 21 and 22 are located at the hot end of conduit 16. An insulating float 33 may be interposed between liquid displacer 31 and gases in hot space 11 to prevent vaporization of the liquid or contamination of the gases.

In operation the sloshing liquid displacer 31 will cyclically and alternately increase and decrease the volume of hot space 11 and cool space 12 resulting in flow of gases within the system through thermal regenerator 17 in accordance with the practice hereinbefore described. Timely opening and closing of a valve 34 located within the ducting will create a small pressure differential between spaces 11 and 12 to maintain sloshing action of the liquid displacer 31 within the conduit 32 once sloshing motion has been initiated.

Thereare a variety of ways in which the method herein disclosed may be employed to use the heat energy of one gas to compress another gas. For example, subsequent to the induction phase, indicated in FIG. 2a, and prior to the compression phase, indicated in FIG. 2b, the working fluid within the cool space 12 may be withdrawn from the system and a second gas substituted therefore. Thus as the process continues the second gas will be heated, by the heat extracted from the initial working fluid during its passage through thermal regenerator 17, expanded within the constant volume system and discharged therefrom at a higher pressure.

An example of an apparatus adapted to compress a second gas is illustrated in FIG. 7 wherein a gas exchanging mechanism with appropriate ducting and valving has been associated with a heat actuated compressor. The compressor A is similar to that of FIG. 3 except that a gas exchange mechanism B has replaced the cooling means. The gas exchange mechanism B comprises a cylinder 50, reciprocating displacement type piston 53, appropriate valves 54, 55, 57, 58 and 59 and ducting 56 between the cool space 12 of the compressor cylinder 10 and regenerator 17. I

In this arrangement, a charge of a cool secondary gas, such as ambient air, is quantitatively substituted for the working fluid after it has .passed through the regenerator 17. In the arrangement shown, when displacer piston 13 is in upward motion inlet check valve 21 is closed, exhaust control valve 54 opened and the residual working gas in hot space 11 of the compressor is drawn into upper space 51 of exchanger cylinder 50. The working gas displaces the cool secondary gas being drawn from lower space 52 of exchanger into cool space 13 of the compressor. As the working fluid is cooled and consequently contracts during passage through regenerator 17 additional Working fluid is drawn into the system through inlet check valve 21, through regenerator 17 and into upper space 51 of exchanger cylinder 50.

Closure of exhaust control valve 54 and one-way flow characteristic of check valve 57 isolate the fixed volume system of the compressor A from exchanger mechanism B. Subsequent downward motion .of displacer piston 13 moves the secondary gas from cool space 12 through check valve 58 and regenerator 17 whence it is heated, expanded and exhausted at an increased pressure through exhaust check valve 22, as indicated by gas flow arrow 4. Meanwhile exchanger piston 53 is returned upwardly by a spring or other return mechanism 60 exhausting the cooled working fluid in upper space 51 through check valve 59 against little or no pressure head, as indicated by gas flow arrow 2. Opening of inlet control valve 55 simultaneously with upward movement of piston 53 permits a fresh quantity of cool secondary gas to be drawn into lower space 52 of exchanger cylinder 50, as indicated by gas flow arrow 3. The apparatus has thus returned to the condition preparatory to another cycle commencing with upward movement of displacer piston 13.

FIG. 8 illustrates an arrangement wherein two gas compressors C and D operating in accordance with the above described method are so integrated through a common heat exchanger 40 that heat flow is effected between the working fluids of the adjacent compressors in coordinated cyclical phases. Heat is transferred from the working fluid of one compressor C during its decompression and induction phases, as indicated by heat energy flow arrows 5, through the heat conductive separator 41 of common heat exchanger 40, to the working fluid of a second compressor D, as indicated by heat energy flow arrow 6. The compression and expulsion phases of the second compressor D are synchronized with the opposite phases of the first compressor C. Heat is thus not stored in a regenerator for subsequent release to a working fluid but is a transient transferral from the working fluid of one compressor system to another.

Whereas certain forms of the invention have been shown and described, it should be understood that this description should be taken in an illustrative or diagrammatic sense only. There are many variations and modifications which will be apparent to those skilled in the art which will not depart from the scope and spirit of the invention. I, therefore, do not wish to be limited to the precise details of construction set forth, but desire to avail myself of such variations and modifications as come within the scope of the appended claims.

What is claimed is:

1. The method of compressing gases comprising the steps of:

moving gas from a first temperature and first pressure condition into a first interior space while transferring heat therefrom to a heat storage means; moving said gas from said first interior space to a second interior space while transferring heat thereto from said storage means, the total volumetric capacity of said first and second spaces being maintained constant; continually removing gas upon achieving a second pressure exceeding said first pressure; and

moving portion of gas remaining in said second interior space at said second pressure back into said first interior space while transferring heat therefrom to said heat storage means.

2. The method of compressing gases in accordance with claim 1 in which gas is subjected to further cooling within said first interior space.

3. The method of compressing gases in accordance with claim 2 in which said further cooling of said gas within said first interior space is effected by exposure of said gas to a fluid within said first interior space.

4. The method of compressing gases in accordance with claim 2 in which said further cooling of said gas within said first interior space is effected by exposure of said gas to a liquid within said first interior space.

5. The method of compressing gases in accordance with claim 2 in which said further cooling of said gas within said first interior space is effected by addition of a predetermined amount of gas at a lower temperature to the gas within said first interior space.

6. The method of compressing gases comprising the steps of:

moving gas from a first temperature and first pressure condition into a first interior space while transferring heat therefrom to a heat storage means;

exposing said gas within said first interior space to a fluid chemically reactive therewith;

moving said gas from said first interior space into a second interior space While transferring heat thereto from said heat storage means, the total volumetric capacity of the first and second interior spaces being maintained constant;

continually removing gas upon achieving a second pressure exceeding said first pressure; and

moving portion of gas remaining in said second interior space at said second pressure back into said first interior space while transferring heat therefrom to said heat storage means.

7. The method of compressing gases in accordance with claim 6 in which said fluid is endothermically reactive with said gas upon exposure thereto within said first interior space.

8. The method of compressing gases comprising the steps of:

moving a first gas from a first temperature and first pressure condition into a first interior space while transferring heat therefrom to a heat storage means;

substitution of a second gas for said first gas within said first interior space;

moving said second gas from said first interior space into a second interior space while transferring heat thereto from said heat storage means, the total volumetric capacity of the first and second interior spaces being maintained constant;

continually removing said second gas upon achieving a second pressure exceeding said first pressure; and

moving portion of gas remaining in said second interior space at said second pressure back into said first interior space while transferring heat therefrom to said heat storage means.

9. An apparatus for compressing gases using thermal expansion and compression of the gas being compressed compnsmg:

a constant volume system including a first variable volume interior space accomodating gases therein and having a cooling means therein by which gas within said first space is cooled; at second variable volume interior space accomodating gases therein; elongated gas-conveying extensions of said spaces terminating at a heat storage means for storing heat transmitted from and transmitting heat to gas passing therethrough, said heat storage means adapted to divide each extension and space associated therewith into a hot gas section and a cool gas section on the opposite sides of said heat storage means; a valved entrance through which gas is admitted into said hot gas section; a valved exit through which gas is expelled from said system; and

means for alternately and simultaneously increasing and decreasing volumes of said first and said second interior spaces.

10. An apparatus for compressing gases in accordance with claim 9 in which said valved entrance and said valved exit are pressure responsive one-way valves.

11. An apparatus for compressing gases in accordance with claim 9 in which said cooling means is a refrigEmt cooled surface.

12. An apparatus for compressing gases in accordance with claim 9 in which said cooling means is a liquid sprayed into said first interior space to effect intimate contact between said liquid coolant and gases within said chamber; a displacement type piston within said chamber defining a first and a second interior space, said piston preventing transfer of heat and gas between said spaces; a cooling means by which gas within said first space is cooled; a thermal regenerator; gas conveying passages connecting said regenerator to said first and second spaces; valves through which gas is admitted into and expelled from said system; and

means for imparting axially reciprocating movement to said piston within said cylindrical chamber.

15. A gas compressor in accordance with claim 14 in which said thermal regenerator is circumferentially disposed about said cylindrical chamber.

16. A gas compressor in accordance with claim 14 in which said cooling means is a liquid coolant sprayed into said first interior space.

17. A gas compressor comprising: a constant volume system including a closed cylindrical chamber; a piston within said chamber defining a first and a second interior space, said piston containing a thermal regenerator therein through which gases may flow between said spaces; a cooling means by which gas within said first space is cooled; valves ROBERT M. WALKER, Primary Examiner through which gas is admitted into and expelled from said second space; and

means for imparting axially reciprocating movement to said piston within said cylindrical chamber.

18. An apparatus for compressing gases using the heat energy from another gas comprising:

a gas compressor including a constant volume system having a closed cylindrical chamber, a displacement type piston within said chamber defining a first space and a second space said piston preventing transfer of heat and gas between said spaces, a thermal regenerator for storing heat transmitted thereto from and transmitting heat to gas passing therethrough, elongated gas conveying extensions of said spaces terminating at said thermal regenerator which is thereby adapted to divide each extension and space associated therewith into a hot gas section and a cool gas section on opposite sides of said regenerator, valves through which gas is admitted into and expelled from said compressor, and means for imparting axially reciprocating movement to said piston 'within said cylindrical chamber; and

a gas exchange mechanism including a constant volume system having a closed cylindrical chamber, a displacement type piston within said chamber defining a third space and a fouith space said piston preventing transfer of gases between said spaces, gas conveying passages connecting said third and fourth spaces to said cool gas section of said gas compressor, valves which selectively isolate said constant volume system of said compressor from said constant volume system of said gas exchange mechanism, valves through which gases are admitted into and expelled from said gas exchange mechanism, and means for imparting axially reciprocating movement to said piston within said cylindrical chamber.

References Cited UNITED STATES PATENTS 3,413,815 12/196 8 'Granryd 62-6 

